The most effective marketing story isn't the one you tell to someone in your audience, it's the one the person tells himself.
Consider this no parking sign. Instead of stating the fine, the signmaker states the range of the fine. At this point, it's up to the observer to have a conversation with himself. "Well, maybe I'll just get a $50 fine. Hmmm, why would that happen? With my luck, it'll be the maximum… I'll just park somewhere else."
It's not an announcement, it's an invitation to a little internal drama.
Too often, we don't give people a chance to fill in the blanks.